When a trades client's marketing line grows, the accountant is usually the first to notice and the least equipped to judge it. The invoices say "Google Ads," "SEO services" or "digital marketing package." None of them say whether the money worked. This guide gives accountants and bookkeepers five numbers that turn marketing into something you can test, plus worked examples using typical trades jobs.
None of this is about running marketing. It's about asking questions that make a client's marketing accountable.
The five numbers to ask for
Ask the client, or their marketing provider, for these figures each month:
- Total marketing spend. Every dollar: platform ad spend, agency fees, directory listings, printed flyers, vehicle wraps if newly bought. Agencies often report only the part they control.
- Genuine enquiries. Calls, texts and emails from potential customers, after removing spam, sales calls and job applicants.
- Booked jobs. Enquiries that became scheduled, paid work.
- Average job value for those booked jobs.
- Contribution margin per job. Revenue minus direct labour, materials and subcontract costs.
You likely have the fifth already, or can estimate it from the client's statements. The other four depend on the client keeping basic records. If they can't produce them, the marketing can't be judged, which is itself a useful finding.
Cost per booked job
This is the single most useful marketing figure for an accountant.
Cost per booked job = total marketing spend ÷ booked jobs from marketing
Example: a drain and plumbing company. It spends $2,400 in a month on marketing and books 24 jobs from it. Cost per booked job is $100. If an average job brings in $650 and contributes $260 after labour and parts, each job leaves $160 after marketing.
Same company, bad month. Spend stays at $2,400, but only 8 jobs are booked. Cost per booked job rises to $300, higher than the $260 contribution. Each marketing-won job now loses $40 before overhead.
The second month isn't necessarily a crisis; a single slow month happens. Three in a row is a conversation.
Break-even marketing spend
Turn the question around: how much can this business afford to spend to win a job?
Break-even cost per job = average contribution per job
Break-even monthly spend = contribution per job × booked jobs the business can handle
Example: an HVAC replacement company. Average replacement job: $9,500. Contribution after equipment and labour: $3,300. The company can install 20 systems a month.
- The theoretical ceiling for marketing spend is $66,000 a month, which would leave nothing for overhead or profit, so it's only a ceiling.
- A healthier target might be to keep marketing at a quarter of contribution or less: about $825 per job, or $16,500 a month at full capacity.
The point isn't the specific ratio. It's that the client and their marketer should agree a target cost per booked job, and you can check it.
Payback and lifetime value
Some trades win repeat customers: maintenance agreements, annual inspections, water-heater replacement every decade, the same homeowner calling for every problem. For those businesses, the first job isn't the whole return.
Example: a heating company with maintenance plans. A new customer's first service call contributes $120. Half of new customers sign a maintenance plan worth $180 a year in contribution and stay an average of four years. The expected contribution per new customer is $120 + (0.5 × $180 × 4) = $480.
That changes what "affordable" means. A cost per booked job of $200 looks like a loss against $120, but a sound investment against $480. Ask the client which figure their marketing provider is using, and whether they're tracking maintenance sign-ups to confirm it.
Be cautious, though. Lifetime value is an estimate, and it's easy to inflate. Insist on the client's own retention history rather than industry averages.
Seasonality: compare like with like
Ontario trades are strongly seasonal. Heating demand peaks in winter and cooling in summer; exterior trades compress their year into the warmer months. Statistics Canada reports that 58% of Ontario households heated primarily with natural gas in 2023 (Table 38-10-0286-01), so furnace and boiler work is a large share of the trades economy, and it's all concentrated in the cold months.
For accountants, that means:
- compare January with last January, not with last June
- expect cost per booked job to rise in shoulder months, when demand falls but competitors keep bidding
- watch for clients who stop all marketing in the slow season and then pay a premium to restart it
A useful question is: "What happened to cost per booked job in your slowest quarter last year?" If nobody knows, that's the next thing to measure.
Warning signs in the books
These patterns often mean marketing is quietly losing money:
- Several marketing vendors billing monthly, none able to say what the others do.
- Ad spend billed through an agency at a markup, rather than directly to the client's own platform account. Check whether the client can see the platform invoices.
- Marketing growing faster than revenue for two or more quarters.
- Reports full of impressions and clicks, with no booked-job figure anywhere.
- Long contracts with exit penalties for small businesses.
- The client can't log into their own accounts. Our digital assets checklist explains why that matters.
A one-page monthly check
If the client agrees, ask for a single page each month with these lines. It's the format of our advisor-ready reports, but any competent provider can produce it.
| Line | This month | Same month last year |
|---|---|---|
| Total marketing spend | ||
| Genuine enquiries | ||
| Booked jobs | ||
| Average job value | ||
| Cost per booked job | ||
| What changed |
With that page beside the monthly figures, you can see in under five minutes whether marketing is pulling its weight.
What accountants shouldn't do
Stay on the numbers. Recommending platforms, budgets, agencies or tactics moves you into marketing advice you're not paid or insured for. If the numbers suggest a problem, the next step is a referral to a specialist, done properly. The referral partnership playbook explains how, and our accountant referrals page describes how we handle it. We're not an accounting firm and never comment on tax or bookkeeping; the arithmetic in this guide is there to help you ask good questions.
Frequently asked questions
Isn't this the marketer's job, not the accountant's?
Running the marketing is. But accountants are often the only people who see marketing cost beside revenue and margin. Asking a few sharp questions is well within an accountant's role; deciding on platforms and budgets isn't.
What's a reasonable cost per booked job?
There's no universal figure. It depends on job value and margin. The useful test is whether cost per booked job sits comfortably below what an average job contributes after direct costs.
How long before marketing should pay for itself?
Paid search should show a measurable cost per job within a couple of months. Search visibility and reviews take longer and keep working afterwards, so judge them over six to twelve months.
What if the client can't tell where jobs come from?
That's the first problem to fix. Call tracking, asking every caller how they found the business and recording the answer in the job system are inexpensive and transform the quality of the numbers.